Talking Frog Box using PIC16F870

This device 'listens' to a conversations and then interjects words and phrases at inappropriate times. I got this box at a local thrift store for $1.50 (special, this week only). It has a nice hinged top and a place to insert a panel with a designed glued to it. Ok, so I found this frog on the net and dug up the Egyption boarder from somewhere on my hard drive - viola, Egyption Frog Box! Starting from the ideas at this site, I tried using a single comparator ic to digitize sound. Very simply put, the incomming audio is sent to one input of the comparator. The other input connects back to the PIC chip via a simple r/c network. The PIC reads the output of the comparator and then outputs a zero or one into the r/c network. This causes the voltage from the r/c to 'track' the incomming audio signal.
Talking Frog Box using PIC16F870 - schematic

As each bit is output, it is also stored in memory for later playback. This allows the use of some really, really cheap, (aw heck, I got them for free) single bit DRAM chip to store the sound. Here is what it all does: When a loud sound is heard with a pause before and after it (indicating some short word, phrase, or explitive), this device records the sound in one of eight memory banks. Then, at random times, when it detects another slight pause in the converstation, it plays out one of the recorded sounds. This unit has now succeeded in really anoying several people. Further experimentation in single-bit encoding is now in progress here. If you are doing some work in this area, or are just interested in using some of this technology, let me know. Here is the schematic as it now and the Source and Object files they stand at present. I have already mounted a small model airplane servo to raise the lid when it talks, but this has not been added to the design as yet.

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